drivers/xen/xen-scsiback.c

   1 /*
   2  * Xen SCSI backend driver
   3  *
   4  * Copyright (c) 2008, FUJITSU Limited
   5  *
   6  * Based on the blkback driver code.
   7  * Adaption to kernel taget core infrastructure taken from vhost/scsi.c
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License version 2
  11  * as published by the Free Software Foundation; or, when distributed
  12  * separately from the Linux kernel or incorporated into other
  13  * software packages, subject to the following license:
  14  *
  15  * Permission is hereby granted, free of charge, to any person obtaining a copy
  16  * of this source file (the "Software"), to deal in the Software without
  17  * restriction, including without limitation the rights to use, copy, modify,
  18  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  19  * and to permit persons to whom the Software is furnished to do so, subject to
  20  * the following conditions:
  21  *
  22  * The above copyright notice and this permission notice shall be included in
  23  * all copies or substantial portions of the Software.
  24  *
  25  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  26  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  27  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  28  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  29  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  30  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  31  * IN THE SOFTWARE.
  32  */
  33
  34 #define pr_fmt(fmt) "xen-pvscsi: " fmt
  35
  36 #include <stdarg.h>
  37
  38 #include <linux/module.h>
  39 #include <linux/utsname.h>
  40 #include <linux/interrupt.h>
  41 #include <linux/slab.h>
  42 #include <linux/wait.h>
  43 #include <linux/sched.h>
  44 #include <linux/list.h>
  45 #include <linux/gfp.h>
  46 #include <linux/delay.h>
  47 #include <linux/spinlock.h>
  48 #include <linux/configfs.h>
  49
  50 #include <generated/utsrelease.h>
  51
  52 #include <scsi/scsi_host.h> /* SG_ALL */
  53
  54 #include <target/target_core_base.h>
  55 #include <target/target_core_fabric.h>
  56 #include <target/target_core_fabric_configfs.h>
  57
  58 #include <asm/hypervisor.h>
  59
  60 #include <xen/xen.h>
  61 #include <xen/balloon.h>
  62 #include <xen/events.h>
  63 #include <xen/xenbus.h>
  64 #include <xen/grant_table.h>
  65 #include <xen/page.h>
  66
  67 #include <xen/interface/grant_table.h>
  68 #include <xen/interface/io/vscsiif.h>
  69
  70 #define VSCSI_VERSION   "v0.1"
  71 #define VSCSI_NAMELEN   32
  72
  73 struct ids_tuple {
  74         unsigned int hst;               /* host    */
  75         unsigned int chn;               /* channel */
  76         unsigned int tgt;               /* target  */
  77         unsigned int lun;               /* LUN     */
  78 };
  79
  80 struct v2p_entry {
  81         struct ids_tuple v;             /* translate from */
  82         struct scsiback_tpg *tpg;       /* translate to   */
  83         unsigned int lun;
  84         struct kref kref;
  85         struct list_head l;
  86 };
  87
  88 struct vscsibk_info {
  89         struct xenbus_device *dev;
  90
  91         domid_t domid;
  92         unsigned int irq;
  93
  94         struct vscsiif_back_ring ring;
  95         int ring_error;
  96
  97         spinlock_t ring_lock;
  98         atomic_t nr_unreplied_reqs;
  99
 100         spinlock_t v2p_lock;
 101         struct list_head v2p_entry_lists;
 102
 103         wait_queue_head_t waiting_to_free;
 104 };
 105
 106 /* theoretical maximum of grants for one request */
 107 #define VSCSI_MAX_GRANTS        (SG_ALL + VSCSIIF_SG_TABLESIZE)
 108
 109 /*
 110  * VSCSI_GRANT_BATCH is the maximum number of grants to be processed in one
 111  * call to map/unmap grants. Don't choose it too large, as there are arrays
 112  * with VSCSI_GRANT_BATCH elements allocated on the stack.
 113  */
 114 #define VSCSI_GRANT_BATCH       16
 115
 116 struct vscsibk_pend {
 117         uint16_t rqid;
 118
 119         uint8_t cmnd[VSCSIIF_MAX_COMMAND_SIZE];
 120         uint8_t cmd_len;
 121
 122         uint8_t sc_data_direction;
 123         uint16_t n_sg;          /* real length of SG list */
 124         uint16_t n_grants;      /* SG pages and potentially SG list */
 125         uint32_t data_len;
 126         uint32_t result;
 127
 128         struct vscsibk_info *info;
 129         struct v2p_entry *v2p;
 130         struct scatterlist *sgl;
 131
 132         uint8_t sense_buffer[VSCSIIF_SENSE_BUFFERSIZE];
 133
 134         grant_handle_t grant_handles[VSCSI_MAX_GRANTS];
 135         struct page *pages[VSCSI_MAX_GRANTS];
 136
 137         struct se_cmd se_cmd;
 138 };
 139
 140 struct scsiback_tmr {
 141         atomic_t tmr_complete;
 142         wait_queue_head_t tmr_wait;
 143 };
 144
 145 struct scsiback_nexus {
 146         /* Pointer to TCM session for I_T Nexus */
 147         struct se_session *tvn_se_sess;
 148 };
 149
 150 struct scsiback_tport {
 151         /* SCSI protocol the tport is providing */
 152         u8 tport_proto_id;
 153         /* Binary World Wide unique Port Name for pvscsi Target port */
 154         u64 tport_wwpn;
 155         /* ASCII formatted WWPN for pvscsi Target port */
 156         char tport_name[VSCSI_NAMELEN];
 157         /* Returned by scsiback_make_tport() */
 158         struct se_wwn tport_wwn;
 159 };
 160
 161 struct scsiback_tpg {
 162         /* scsiback port target portal group tag for TCM */
 163         u16 tport_tpgt;
 164         /* track number of TPG Port/Lun Links wrt explicit I_T Nexus shutdown */
 165         int tv_tpg_port_count;
 166         /* xen-pvscsi references to tpg_nexus, protected by tv_tpg_mutex */
 167         int tv_tpg_fe_count;
 168         /* list for scsiback_list */
 169         struct list_head tv_tpg_list;
 170         /* Used to protect access for tpg_nexus */
 171         struct mutex tv_tpg_mutex;
 172         /* Pointer to the TCM pvscsi I_T Nexus for this TPG endpoint */
 173         struct scsiback_nexus *tpg_nexus;
 174         /* Pointer back to scsiback_tport */
 175         struct scsiback_tport *tport;
 176         /* Returned by scsiback_make_tpg() */
 177         struct se_portal_group se_tpg;
 178         /* alias used in xenstore */
 179         char param_alias[VSCSI_NAMELEN];
 180         /* list of info structures related to this target portal group */
 181         struct list_head info_list;
 182 };
 183
 184 #define SCSIBACK_INVALID_HANDLE (~0)
 185
 186 static bool log_print_stat;
 187 module_param(log_print_stat, bool, 0644);
 188
 189 static int scsiback_max_buffer_pages = 1024;
 190 module_param_named(max_buffer_pages, scsiback_max_buffer_pages, int, 0644);
 191 MODULE_PARM_DESC(max_buffer_pages,
 192 "Maximum number of free pages to keep in backend buffer");
 193
 194 static struct kmem_cache *scsiback_cachep;
 195 static DEFINE_SPINLOCK(free_pages_lock);
 196 static int free_pages_num;
 197 static LIST_HEAD(scsiback_free_pages);
 198
 199 /* Global spinlock to protect scsiback TPG list */
 200 static DEFINE_MUTEX(scsiback_mutex);
 201 static LIST_HEAD(scsiback_list);
 202
 203 static void scsiback_get(struct vscsibk_info *info)
 204 {
 205         atomic_inc(&info->nr_unreplied_reqs);
 206 }
 207
 208 static void scsiback_put(struct vscsibk_info *info)
 209 {
 210         if (atomic_dec_and_test(&info->nr_unreplied_reqs))
 211                 wake_up(&info->waiting_to_free);
 212 }
 213
 214 static void put_free_pages(struct page **page, int num)
 215 {
 216         unsigned long flags;
 217         int i = free_pages_num + num, n = num;
 218
 219         if (num == 0)
 220                 return;
 221         if (i > scsiback_max_buffer_pages) {
 222                 n = min(num, i - scsiback_max_buffer_pages);
 223                 gnttab_free_pages(n, page + num - n);
 224                 n = num - n;
 225         }
 226         spin_lock_irqsave(&free_pages_lock, flags);
 227         for (i = 0; i < n; i++)
 228                 list_add(&page[i]->lru, &scsiback_free_pages);
 229         free_pages_num += n;
 230         spin_unlock_irqrestore(&free_pages_lock, flags);
 231 }
 232
 233 static int get_free_page(struct page **page)
 234 {
 235         unsigned long flags;
 236
 237         spin_lock_irqsave(&free_pages_lock, flags);
 238         if (list_empty(&scsiback_free_pages)) {
 239                 spin_unlock_irqrestore(&free_pages_lock, flags);
 240                 return gnttab_alloc_pages(1, page);
 241         }
 242         page[0] = list_first_entry(&scsiback_free_pages, struct page, lru);
 243         list_del(&page[0]->lru);
 244         free_pages_num--;
 245         spin_unlock_irqrestore(&free_pages_lock, flags);
 246         return 0;
 247 }
 248
 249 static unsigned long vaddr_page(struct page *page)
 250 {
 251         unsigned long pfn = page_to_pfn(page);
 252
 253         return (unsigned long)pfn_to_kaddr(pfn);
 254 }
 255
 256 static unsigned long vaddr(struct vscsibk_pend *req, int seg)
 257 {
 258         return vaddr_page(req->pages[seg]);
 259 }
 260
 261 static void scsiback_print_status(char *sense_buffer, int errors,
 262                                         struct vscsibk_pend *pending_req)
 263 {
 264         struct scsiback_tpg *tpg = pending_req->v2p->tpg;
 265
 266         pr_err("[%s:%d] cmnd[0]=%02x -> st=%02x msg=%02x host=%02x drv=%02x\n",
 267                tpg->tport->tport_name, pending_req->v2p->lun,
 268                pending_req->cmnd[0], status_byte(errors), msg_byte(errors),
 269                host_byte(errors), driver_byte(errors));
 270 }
 271
 272 static void scsiback_fast_flush_area(struct vscsibk_pend *req)
 273 {
 274         struct gnttab_unmap_grant_ref unmap[VSCSI_GRANT_BATCH];
 275         struct page *pages[VSCSI_GRANT_BATCH];
 276         unsigned int i, invcount = 0;
 277         grant_handle_t handle;
 278         int err;
 279
 280         kfree(req->sgl);
 281         req->sgl = NULL;
 282         req->n_sg = 0;
 283
 284         if (!req->n_grants)
 285                 return;
 286
 287         for (i = 0; i < req->n_grants; i++) {
 288                 handle = req->grant_handles[i];
 289                 if (handle == SCSIBACK_INVALID_HANDLE)
 290                         continue;
 291                 gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i),
 292                                     GNTMAP_host_map, handle);
 293                 req->grant_handles[i] = SCSIBACK_INVALID_HANDLE;
 294                 pages[invcount] = req->pages[i];
 295                 put_page(pages[invcount]);
 296                 invcount++;
 297                 if (invcount < VSCSI_GRANT_BATCH)
 298                         continue;
 299                 err = gnttab_unmap_refs(unmap, NULL, pages, invcount);
 300                 BUG_ON(err);
 301                 invcount = 0;
 302         }
 303
 304         if (invcount) {
 305                 err = gnttab_unmap_refs(unmap, NULL, pages, invcount);
 306                 BUG_ON(err);
 307         }
 308
 309         put_free_pages(req->pages, req->n_grants);
 310         req->n_grants = 0;
 311 }
 312
 313 static void scsiback_free_translation_entry(struct kref *kref)
 314 {
 315         struct v2p_entry *entry = container_of(kref, struct v2p_entry, kref);
 316         struct scsiback_tpg *tpg = entry->tpg;
 317
 318         mutex_lock(&tpg->tv_tpg_mutex);
 319         tpg->tv_tpg_fe_count--;
 320         mutex_unlock(&tpg->tv_tpg_mutex);
 321
 322         kfree(entry);
 323 }
 324
 325 static void scsiback_do_resp_with_sense(char *sense_buffer, int32_t result,
 326                         uint32_t resid, struct vscsibk_pend *pending_req)
 327 {
 328         struct vscsiif_response *ring_res;
 329         struct vscsibk_info *info = pending_req->info;
 330         int notify;
 331         struct scsi_sense_hdr sshdr;
 332         unsigned long flags;
 333         unsigned len;
 334
 335         spin_lock_irqsave(&info->ring_lock, flags);
 336
 337         ring_res = RING_GET_RESPONSE(&info->ring, info->ring.rsp_prod_pvt);
 338         info->ring.rsp_prod_pvt++;
 339
 340         ring_res->rslt   = result;
 341         ring_res->rqid   = pending_req->rqid;
 342
 343         if (sense_buffer != NULL &&
 344             scsi_normalize_sense(sense_buffer, VSCSIIF_SENSE_BUFFERSIZE,
 345                                  &sshdr)) {
 346                 len = min_t(unsigned, 8 + sense_buffer[7],
 347                             VSCSIIF_SENSE_BUFFERSIZE);
 348                 memcpy(ring_res->sense_buffer, sense_buffer, len);
 349                 ring_res->sense_len = len;
 350         } else {
 351                 ring_res->sense_len = 0;
 352         }
 353
 354         ring_res->residual_len = resid;
 355
 356         RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&info->ring, notify);
 357         spin_unlock_irqrestore(&info->ring_lock, flags);
 358
 359         if (notify)
 360                 notify_remote_via_irq(info->irq);
 361
 362         if (pending_req->v2p)
 363                 kref_put(&pending_req->v2p->kref,
 364                          scsiback_free_translation_entry);
 365 }
 366
 367 static void scsiback_cmd_done(struct vscsibk_pend *pending_req)
 368 {
 369         struct vscsibk_info *info = pending_req->info;
 370         unsigned char *sense_buffer;
 371         unsigned int resid;
 372         int errors;
 373
 374         sense_buffer = pending_req->sense_buffer;
 375         resid        = pending_req->se_cmd.residual_count;
 376         errors       = pending_req->result;
 377
 378         if (errors && log_print_stat)
 379                 scsiback_print_status(sense_buffer, errors, pending_req);
 380
 381         scsiback_fast_flush_area(pending_req);
 382         scsiback_do_resp_with_sense(sense_buffer, errors, resid, pending_req);
 383         scsiback_put(info);
 384 }
 385
 386 static void scsiback_cmd_exec(struct vscsibk_pend *pending_req)
 387 {
 388         struct se_cmd *se_cmd = &pending_req->se_cmd;
 389         struct se_session *sess = pending_req->v2p->tpg->tpg_nexus->tvn_se_sess;
 390         int rc;
 391
 392         memset(pending_req->sense_buffer, 0, VSCSIIF_SENSE_BUFFERSIZE);
 393
 394         memset(se_cmd, 0, sizeof(*se_cmd));
 395
 396         scsiback_get(pending_req->info);
 397         se_cmd->tag = pending_req->rqid;
 398         rc = target_submit_cmd_map_sgls(se_cmd, sess, pending_req->cmnd,
 399                         pending_req->sense_buffer, pending_req->v2p->lun,
 400                         pending_req->data_len, 0,
 401                         pending_req->sc_data_direction, 0,
 402                         pending_req->sgl, pending_req->n_sg,
 403                         NULL, 0, NULL, 0);
 404         if (rc < 0) {
 405                 transport_send_check_condition_and_sense(se_cmd,
 406                                 TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
 407                 transport_generic_free_cmd(se_cmd, 0);
 408         }
 409 }
 410
 411 static int scsiback_gnttab_data_map_batch(struct gnttab_map_grant_ref *map,
 412         struct page **pg, grant_handle_t *grant, int cnt)
 413 {
 414         int err, i;
 415
 416         if (!cnt)
 417                 return 0;
 418
 419         err = gnttab_map_refs(map, NULL, pg, cnt);
 420         BUG_ON(err);
 421         for (i = 0; i < cnt; i++) {
 422                 if (unlikely(map[i].status != GNTST_okay)) {
 423                         pr_err("invalid buffer -- could not remap it\n");
 424                         map[i].handle = SCSIBACK_INVALID_HANDLE;
 425                         err = -ENOMEM;
 426                 } else {
 427                         get_page(pg[i]);
 428                 }
 429                 grant[i] = map[i].handle;
 430         }
 431         return err;
 432 }
 433
 434 static int scsiback_gnttab_data_map_list(struct vscsibk_pend *pending_req,
 435                         struct scsiif_request_segment *seg, struct page **pg,
 436                         grant_handle_t *grant, int cnt, u32 flags)
 437 {
 438         int mapcount = 0, i, err = 0;
 439         struct gnttab_map_grant_ref map[VSCSI_GRANT_BATCH];
 440         struct vscsibk_info *info = pending_req->info;
 441
 442         for (i = 0; i < cnt; i++) {
 443                 if (get_free_page(pg + mapcount)) {
 444                         put_free_pages(pg, mapcount);
 445                         pr_err("no grant page\n");
 446                         return -ENOMEM;
 447                 }
 448                 gnttab_set_map_op(&map[mapcount], vaddr_page(pg[mapcount]),
 449                                   flags, seg[i].gref, info->domid);
 450                 mapcount++;
 451                 if (mapcount < VSCSI_GRANT_BATCH)
 452                         continue;
 453                 err = scsiback_gnttab_data_map_batch(map, pg, grant, mapcount);
 454                 pg += mapcount;
 455                 grant += mapcount;
 456                 pending_req->n_grants += mapcount;
 457                 if (err)
 458                         return err;
 459                 mapcount = 0;
 460         }
 461         err = scsiback_gnttab_data_map_batch(map, pg, grant, mapcount);
 462         pending_req->n_grants += mapcount;
 463         return err;
 464 }
 465
 466 static int scsiback_gnttab_data_map(struct vscsiif_request *ring_req,
 467                                         struct vscsibk_pend *pending_req)
 468 {
 469         u32 flags;
 470         int i, err, n_segs, i_seg = 0;
 471         struct page **pg;
 472         struct scsiif_request_segment *seg;
 473         unsigned long end_seg = 0;
 474         unsigned int nr_segments = (unsigned int)ring_req->nr_segments;
 475         unsigned int nr_sgl = 0;
 476         struct scatterlist *sg;
 477         grant_handle_t *grant;
 478
 479         pending_req->n_sg = 0;
 480         pending_req->n_grants = 0;
 481         pending_req->data_len = 0;
 482
 483         nr_segments &= ~VSCSIIF_SG_GRANT;
 484         if (!nr_segments)
 485                 return 0;
 486
 487         if (nr_segments > VSCSIIF_SG_TABLESIZE) {
 488                 pr_debug("invalid parameter nr_seg = %d\n",
 489                         ring_req->nr_segments);
 490                 return -EINVAL;
 491         }
 492
 493         if (ring_req->nr_segments & VSCSIIF_SG_GRANT) {
 494                 err = scsiback_gnttab_data_map_list(pending_req, ring_req->seg,
 495                         pending_req->pages, pending_req->grant_handles,
 496                         nr_segments, GNTMAP_host_map | GNTMAP_readonly);
 497                 if (err)
 498                         return err;
 499                 nr_sgl = nr_segments;
 500                 nr_segments = 0;
 501                 for (i = 0; i < nr_sgl; i++) {
 502                         n_segs = ring_req->seg[i].length /
 503                                  sizeof(struct scsiif_request_segment);
 504                         if ((unsigned)ring_req->seg[i].offset +
 505                             (unsigned)ring_req->seg[i].length > PAGE_SIZE ||
 506                             n_segs * sizeof(struct scsiif_request_segment) !=
 507                             ring_req->seg[i].length)
 508                                 return -EINVAL;
 509                         nr_segments += n_segs;
 510                 }
 511                 if (nr_segments > SG_ALL) {
 512                         pr_debug("invalid nr_seg = %d\n", nr_segments);
 513                         return -EINVAL;
 514                 }
 515         }
 516
 517         /* free of (sgl) in fast_flush_area() */
 518         pending_req->sgl = kmalloc_array(nr_segments,
 519                                         sizeof(struct scatterlist), GFP_KERNEL);
 520         if (!pending_req->sgl)
 521                 return -ENOMEM;
 522
 523         sg_init_table(pending_req->sgl, nr_segments);
 524         pending_req->n_sg = nr_segments;
 525
 526         flags = GNTMAP_host_map;
 527         if (pending_req->sc_data_direction == DMA_TO_DEVICE)
 528                 flags |= GNTMAP_readonly;
 529
 530         pg = pending_req->pages + nr_sgl;
 531         grant = pending_req->grant_handles + nr_sgl;
 532         if (!nr_sgl) {
 533                 seg = ring_req->seg;
 534                 err = scsiback_gnttab_data_map_list(pending_req, seg,
 535                         pg, grant, nr_segments, flags);
 536                 if (err)
 537                         return err;
 538         } else {
 539                 for (i = 0; i < nr_sgl; i++) {
 540                         seg = (struct scsiif_request_segment *)(
 541                               vaddr(pending_req, i) + ring_req->seg[i].offset);
 542                         n_segs = ring_req->seg[i].length /
 543                                  sizeof(struct scsiif_request_segment);
 544                         err = scsiback_gnttab_data_map_list(pending_req, seg,
 545                                 pg, grant, n_segs, flags);
 546                         if (err)
 547                                 return err;
 548                         pg += n_segs;
 549                         grant += n_segs;
 550                 }
 551                 end_seg = vaddr(pending_req, 0) + ring_req->seg[0].offset;
 552                 seg = (struct scsiif_request_segment *)end_seg;
 553                 end_seg += ring_req->seg[0].length;
 554                 pg = pending_req->pages + nr_sgl;
 555         }
 556
 557         for_each_sg(pending_req->sgl, sg, nr_segments, i) {
 558                 sg_set_page(sg, pg[i], seg->length, seg->offset);
 559                 pending_req->data_len += seg->length;
 560                 seg++;
 561                 if (nr_sgl && (unsigned long)seg >= end_seg) {
 562                         i_seg++;
 563                         end_seg = vaddr(pending_req, i_seg) +
 564                                   ring_req->seg[i_seg].offset;
 565                         seg = (struct scsiif_request_segment *)end_seg;
 566                         end_seg += ring_req->seg[i_seg].length;
 567                 }
 568                 if (sg->offset >= PAGE_SIZE ||
 569                     sg->length > PAGE_SIZE ||
 570                     sg->offset + sg->length > PAGE_SIZE)
 571                         return -EINVAL;
 572         }
 573
 574         return 0;
 575 }
 576
 577 static void scsiback_disconnect(struct vscsibk_info *info)
 578 {
 579         wait_event(info->waiting_to_free,
 580                 atomic_read(&info->nr_unreplied_reqs) == 0);
 581
 582         unbind_from_irqhandler(info->irq, info);
 583         info->irq = 0;
 584         xenbus_unmap_ring_vfree(info->dev, info->ring.sring);
 585 }
 586
 587 static void scsiback_device_action(struct vscsibk_pend *pending_req,
 588         enum tcm_tmreq_table act, int tag)
 589 {
 590         int rc, err = FAILED;
 591         struct scsiback_tpg *tpg = pending_req->v2p->tpg;
 592         struct se_cmd *se_cmd = &pending_req->se_cmd;
 593         struct scsiback_tmr *tmr;
 594
 595         tmr = kzalloc(sizeof(struct scsiback_tmr), GFP_KERNEL);
 596         if (!tmr)
 597                 goto out;
 598
 599         init_waitqueue_head(&tmr->tmr_wait);
 600
 601         transport_init_se_cmd(se_cmd, tpg->se_tpg.se_tpg_tfo,
 602                 tpg->tpg_nexus->tvn_se_sess, 0, DMA_NONE, TCM_SIMPLE_TAG,
 603                 &pending_req->sense_buffer[0]);
 604
 605         rc = core_tmr_alloc_req(se_cmd, tmr, act, GFP_KERNEL);
 606         if (rc < 0)
 607                 goto out;
 608
 609         se_cmd->se_tmr_req->ref_task_tag = tag;
 610
 611         if (transport_lookup_tmr_lun(se_cmd, pending_req->v2p->lun) < 0)
 612                 goto out;
 613
 614         transport_generic_handle_tmr(se_cmd);
 615         wait_event(tmr->tmr_wait, atomic_read(&tmr->tmr_complete));
 616
 617         err = (se_cmd->se_tmr_req->response == TMR_FUNCTION_COMPLETE) ?
 618                 SUCCESS : FAILED;
 619
 620 out:
 621         if (tmr) {
 622                 transport_generic_free_cmd(&pending_req->se_cmd, 1);
 623                 kfree(tmr);
 624         }
 625
 626         scsiback_do_resp_with_sense(NULL, err, 0, pending_req);
 627
 628         kmem_cache_free(scsiback_cachep, pending_req);
 629 }
 630
 631 /*
 632   Perform virtual to physical translation
 633 */
 634 static struct v2p_entry *scsiback_do_translation(struct vscsibk_info *info,
 635                         struct ids_tuple *v)
 636 {
 637         struct v2p_entry *entry;
 638         struct list_head *head = &(info->v2p_entry_lists);
 639         unsigned long flags;
 640
 641         spin_lock_irqsave(&info->v2p_lock, flags);
 642         list_for_each_entry(entry, head, l) {
 643                 if ((entry->v.chn == v->chn) &&
 644                     (entry->v.tgt == v->tgt) &&
 645                     (entry->v.lun == v->lun)) {
 646                         kref_get(&entry->kref);
 647                         goto out;
 648                 }
 649         }
 650         entry = NULL;
 651
 652 out:
 653         spin_unlock_irqrestore(&info->v2p_lock, flags);
 654         return entry;
 655 }
 656
 657 static int prepare_pending_reqs(struct vscsibk_info *info,
 658                                 struct vscsiif_request *ring_req,
 659                                 struct vscsibk_pend *pending_req)
 660 {
 661         struct v2p_entry *v2p;
 662         struct ids_tuple vir;
 663
 664         pending_req->rqid       = ring_req->rqid;
 665         pending_req->info       = info;
 666
 667         vir.chn = ring_req->channel;
 668         vir.tgt = ring_req->id;
 669         vir.lun = ring_req->lun;
 670
 671         v2p = scsiback_do_translation(info, &vir);
 672         if (!v2p) {
 673                 pending_req->v2p = NULL;
 674                 pr_debug("the v2p of (chn:%d, tgt:%d, lun:%d) doesn't exist.\n",
 675                         vir.chn, vir.tgt, vir.lun);
 676                 return -ENODEV;
 677         }
 678         pending_req->v2p = v2p;
 679
 680         /* request range check from frontend */
 681         pending_req->sc_data_direction = ring_req->sc_data_direction;
 682         if ((pending_req->sc_data_direction != DMA_BIDIRECTIONAL) &&
 683                 (pending_req->sc_data_direction != DMA_TO_DEVICE) &&
 684                 (pending_req->sc_data_direction != DMA_FROM_DEVICE) &&
 685                 (pending_req->sc_data_direction != DMA_NONE)) {
 686                 pr_debug("invalid parameter data_dir = %d\n",
 687                         pending_req->sc_data_direction);
 688                 return -EINVAL;
 689         }
 690
 691         pending_req->cmd_len = ring_req->cmd_len;
 692         if (pending_req->cmd_len > VSCSIIF_MAX_COMMAND_SIZE) {
 693                 pr_debug("invalid parameter cmd_len = %d\n",
 694                         pending_req->cmd_len);
 695                 return -EINVAL;
 696         }
 697         memcpy(pending_req->cmnd, ring_req->cmnd, pending_req->cmd_len);
 698
 699         return 0;
 700 }
 701
 702 static int scsiback_do_cmd_fn(struct vscsibk_info *info)
 703 {
 704         struct vscsiif_back_ring *ring = &info->ring;
 705         struct vscsiif_request ring_req;
 706         struct vscsibk_pend *pending_req;
 707         RING_IDX rc, rp;
 708         int err, more_to_do;
 709         uint32_t result;
 710
 711         rc = ring->req_cons;
 712         rp = ring->sring->req_prod;
 713         rmb();  /* guest system is accessing ring, too */
 714
 715         if (RING_REQUEST_PROD_OVERFLOW(ring, rp)) {
 716                 rc = ring->rsp_prod_pvt;
 717                 pr_warn("Dom%d provided bogus ring requests (%#x - %#x = %u). Halting ring processing\n",
 718                            info->domid, rp, rc, rp - rc);
 719                 info->ring_error = 1;
 720                 return 0;
 721         }
 722
 723         while ((rc != rp)) {
 724                 if (RING_REQUEST_CONS_OVERFLOW(ring, rc))
 725                         break;
 726                 pending_req = kmem_cache_alloc(scsiback_cachep, GFP_KERNEL);
 727                 if (!pending_req)
 728                         return 1;
 729
 730                 ring_req = *RING_GET_REQUEST(ring, rc);
 731                 ring->req_cons = ++rc;
 732
 733                 err = prepare_pending_reqs(info, &ring_req, pending_req);
 734                 if (err) {
 735                         switch (err) {
 736                         case -ENODEV:
 737                                 result = DID_NO_CONNECT;
 738                                 break;
 739                         default:
 740                                 result = DRIVER_ERROR;
 741                                 break;
 742                         }
 743                         scsiback_do_resp_with_sense(NULL, result << 24, 0,
 744                                                     pending_req);
 745                         kmem_cache_free(scsiback_cachep, pending_req);
 746                         return 1;
 747                 }
 748
 749                 switch (ring_req.act) {
 750                 case VSCSIIF_ACT_SCSI_CDB:
 751                         if (scsiback_gnttab_data_map(&ring_req, pending_req)) {
 752                                 scsiback_fast_flush_area(pending_req);
 753                                 scsiback_do_resp_with_sense(NULL,
 754                                         DRIVER_ERROR << 24, 0, pending_req);
 755                                 kmem_cache_free(scsiback_cachep, pending_req);
 756                         } else {
 757                                 scsiback_cmd_exec(pending_req);
 758                         }
 759                         break;
 760                 case VSCSIIF_ACT_SCSI_ABORT:
 761                         scsiback_device_action(pending_req, TMR_ABORT_TASK,
 762                                 ring_req.ref_rqid);
 763                         break;
 764                 case VSCSIIF_ACT_SCSI_RESET:
 765                         scsiback_device_action(pending_req, TMR_LUN_RESET, 0);
 766                         break;
 767                 default:
 768                         pr_err_ratelimited("invalid request\n");
 769                         scsiback_do_resp_with_sense(NULL, DRIVER_ERROR << 24,
 770                                                     0, pending_req);
 771                         kmem_cache_free(scsiback_cachep, pending_req);
 772                         break;
 773                 }
 774
 775                 /* Yield point for this unbounded loop. */
 776                 cond_resched();
 777         }
 778
 779         RING_FINAL_CHECK_FOR_REQUESTS(&info->ring, more_to_do);
 780         return more_to_do;
 781 }
 782
 783 static irqreturn_t scsiback_irq_fn(int irq, void *dev_id)
 784 {
 785         struct vscsibk_info *info = dev_id;
 786
 787         if (info->ring_error)
 788                 return IRQ_HANDLED;
 789
 790         while (scsiback_do_cmd_fn(info))
 791                 cond_resched();
 792
 793         return IRQ_HANDLED;
 794 }
 795
 796 static int scsiback_init_sring(struct vscsibk_info *info, grant_ref_t ring_ref,
 797                         evtchn_port_t evtchn)
 798 {
 799         void *area;
 800         struct vscsiif_sring *sring;
 801         int err;
 802
 803         if (info->irq)
 804                 return -1;
 805
 806         err = xenbus_map_ring_valloc(info->dev, &ring_ref, 1, &area);
 807         if (err)
 808                 return err;
 809
 810         sring = (struct vscsiif_sring *)area;
 811         BACK_RING_INIT(&info->ring, sring, PAGE_SIZE);
 812
 813         err = bind_interdomain_evtchn_to_irq(info->domid, evtchn);
 814         if (err < 0)
 815                 goto unmap_page;
 816
 817         info->irq = err;
 818
 819         err = request_threaded_irq(info->irq, NULL, scsiback_irq_fn,
 820                                    IRQF_ONESHOT, "vscsiif-backend", info);
 821         if (err)
 822                 goto free_irq;
 823
 824         return 0;
 825
 826 free_irq:
 827         unbind_from_irqhandler(info->irq, info);
 828         info->irq = 0;
 829 unmap_page:
 830         xenbus_unmap_ring_vfree(info->dev, area);
 831
 832         return err;
 833 }
 834
 835 static int scsiback_map(struct vscsibk_info *info)
 836 {
 837         struct xenbus_device *dev = info->dev;
 838         unsigned int ring_ref, evtchn;
 839         int err;
 840
 841         err = xenbus_gather(XBT_NIL, dev->otherend,
 842                         "ring-ref", "%u", &ring_ref,
 843                         "event-channel", "%u", &evtchn, NULL);
 844         if (err) {
 845                 xenbus_dev_fatal(dev, err, "reading %s ring", dev->otherend);
 846                 return err;
 847         }
 848
 849         return scsiback_init_sring(info, ring_ref, evtchn);
 850 }
 851
 852 /*
 853   Add a new translation entry
 854 */
 855 static int scsiback_add_translation_entry(struct vscsibk_info *info,
 856                                           char *phy, struct ids_tuple *v)
 857 {
 858         int err = 0;
 859         struct v2p_entry *entry;
 860         struct v2p_entry *new;
 861         struct list_head *head = &(info->v2p_entry_lists);
 862         unsigned long flags;
 863         char *lunp;
 864         unsigned long long unpacked_lun;
 865         struct se_lun *se_lun;
 866         struct scsiback_tpg *tpg_entry, *tpg = NULL;
 867         char *error = "doesn't exist";
 868
 869         lunp = strrchr(phy, ':');
 870         if (!lunp) {
 871                 pr_err("illegal format of physical device %s\n", phy);
 872                 return -EINVAL;
 873         }
 874         *lunp = 0;
 875         lunp++;
 876         err = kstrtoull(lunp, 10, &unpacked_lun);
 877         if (err < 0) {
 878                 pr_err("lun number not valid: %s\n", lunp);
 879                 return err;
 880         }
 881
 882         mutex_lock(&scsiback_mutex);
 883         list_for_each_entry(tpg_entry, &scsiback_list, tv_tpg_list) {
 884                 if (!strcmp(phy, tpg_entry->tport->tport_name) ||
 885                     !strcmp(phy, tpg_entry->param_alias)) {
 886                         mutex_lock(&tpg_entry->se_tpg.tpg_lun_mutex);
 887                         hlist_for_each_entry(se_lun, &tpg_entry->se_tpg.tpg_lun_hlist, link) {
 888                                 if (se_lun->unpacked_lun == unpacked_lun) {
 889                                         if (!tpg_entry->tpg_nexus)
 890                                                 error = "nexus undefined";
 891                                         else
 892                                                 tpg = tpg_entry;
 893                                         break;
 894                                 }
 895                         }
 896                         mutex_unlock(&tpg_entry->se_tpg.tpg_lun_mutex);
 897                         break;
 898                 }
 899         }
 900         if (tpg) {
 901                 mutex_lock(&tpg->tv_tpg_mutex);
 902                 tpg->tv_tpg_fe_count++;
 903                 mutex_unlock(&tpg->tv_tpg_mutex);
 904         }
 905         mutex_unlock(&scsiback_mutex);
 906
 907         if (!tpg) {
 908                 pr_err("%s:%llu %s\n", phy, unpacked_lun, error);
 909                 return -ENODEV;
 910         }
 911
 912         new = kmalloc(sizeof(struct v2p_entry), GFP_KERNEL);
 913         if (new == NULL) {
 914                 err = -ENOMEM;
 915                 goto out_free;
 916         }
 917
 918         spin_lock_irqsave(&info->v2p_lock, flags);
 919
 920         /* Check double assignment to identical virtual ID */
 921         list_for_each_entry(entry, head, l) {
 922                 if ((entry->v.chn == v->chn) &&
 923                     (entry->v.tgt == v->tgt) &&
 924                     (entry->v.lun == v->lun)) {
 925                         pr_warn("Virtual ID is already used. Assignment was not performed.\n");
 926                         err = -EEXIST;
 927                         goto out;
 928                 }
 929
 930         }
 931
 932         /* Create a new translation entry and add to the list */
 933         kref_init(&new->kref);
 934         new->v = *v;
 935         new->tpg = tpg;
 936         new->lun = unpacked_lun;
 937         list_add_tail(&new->l, head);
 938
 939 out:
 940         spin_unlock_irqrestore(&info->v2p_lock, flags);
 941
 942 out_free:
 943         mutex_lock(&tpg->tv_tpg_mutex);
 944         tpg->tv_tpg_fe_count--;
 945         mutex_unlock(&tpg->tv_tpg_mutex);
 946
 947         if (err)
 948                 kfree(new);
 949
 950         return err;
 951 }
 952
 953 static void __scsiback_del_translation_entry(struct v2p_entry *entry)
 954 {
 955         list_del(&entry->l);
 956         kref_put(&entry->kref, scsiback_free_translation_entry);
 957 }
 958
 959 /*
 960   Delete the translation entry specfied
 961 */
 962 static int scsiback_del_translation_entry(struct vscsibk_info *info,
 963                                           struct ids_tuple *v)
 964 {
 965         struct v2p_entry *entry;
 966         struct list_head *head = &(info->v2p_entry_lists);
 967         unsigned long flags;
 968
 969         spin_lock_irqsave(&info->v2p_lock, flags);
 970         /* Find out the translation entry specified */
 971         list_for_each_entry(entry, head, l) {
 972                 if ((entry->v.chn == v->chn) &&
 973                     (entry->v.tgt == v->tgt) &&
 974                     (entry->v.lun == v->lun)) {
 975                         goto found;
 976                 }
 977         }
 978
 979         spin_unlock_irqrestore(&info->v2p_lock, flags);
 980         return 1;
 981
 982 found:
 983         /* Delete the translation entry specfied */
 984         __scsiback_del_translation_entry(entry);
 985
 986         spin_unlock_irqrestore(&info->v2p_lock, flags);
 987         return 0;
 988 }
 989
 990 static void scsiback_do_add_lun(struct vscsibk_info *info, const char *state,
 991                                 char *phy, struct ids_tuple *vir, int try)
 992 {
 993         if (!scsiback_add_translation_entry(info, phy, vir)) {
 994                 if (xenbus_printf(XBT_NIL, info->dev->nodename, state,
 995                                   "%d", XenbusStateInitialised)) {
 996                         pr_err("xenbus_printf error %s\n", state);
 997                         scsiback_del_translation_entry(info, vir);
 998                 }
 999         } else if (!try) {
1000                 xenbus_printf(XBT_NIL, info->dev->nodename, state,
1001                               "%d", XenbusStateClosed);
1002         }
1003 }
1004
1005 static void scsiback_do_del_lun(struct vscsibk_info *info, const char *state,
1006                                 struct ids_tuple *vir)
1007 {
1008         if (!scsiback_del_translation_entry(info, vir)) {
1009                 if (xenbus_printf(XBT_NIL, info->dev->nodename, state,
1010                                   "%d", XenbusStateClosed))
1011                         pr_err("xenbus_printf error %s\n", state);
1012         }
1013 }
1014
1015 #define VSCSIBACK_OP_ADD_OR_DEL_LUN     1
1016 #define VSCSIBACK_OP_UPDATEDEV_STATE    2
1017
1018 static void scsiback_do_1lun_hotplug(struct vscsibk_info *info, int op,
1019                                      char *ent)
1020 {
1021         int err;
1022         struct ids_tuple vir;
1023         char *val;
1024         int device_state;
1025         char phy[VSCSI_NAMELEN];
1026         char str[64];
1027         char state[64];
1028         struct xenbus_device *dev = info->dev;
1029
1030         /* read status */
1031         snprintf(state, sizeof(state), "vscsi-devs/%s/state", ent);
1032         err = xenbus_scanf(XBT_NIL, dev->nodename, state, "%u", &device_state);
1033         if (XENBUS_EXIST_ERR(err))
1034                 return;
1035
1036         /* physical SCSI device */
1037         snprintf(str, sizeof(str), "vscsi-devs/%s/p-dev", ent);
1038         val = xenbus_read(XBT_NIL, dev->nodename, str, NULL);
1039         if (IS_ERR(val)) {
1040                 xenbus_printf(XBT_NIL, dev->nodename, state,
1041                               "%d", XenbusStateClosed);
1042                 return;
1043         }
1044         strlcpy(phy, val, VSCSI_NAMELEN);
1045         kfree(val);
1046
1047         /* virtual SCSI device */
1048         snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", ent);
1049         err = xenbus_scanf(XBT_NIL, dev->nodename, str, "%u:%u:%u:%u",
1050                            &vir.hst, &vir.chn, &vir.tgt, &vir.lun);
1051         if (XENBUS_EXIST_ERR(err)) {
1052                 xenbus_printf(XBT_NIL, dev->nodename, state,
1053                               "%d", XenbusStateClosed);
1054                 return;
1055         }
1056
1057         switch (op) {
1058         case VSCSIBACK_OP_ADD_OR_DEL_LUN:
1059                 switch (device_state) {
1060                 case XenbusStateInitialising:
1061                         scsiback_do_add_lun(info, state, phy, &vir, 0);
1062                         break;
1063                 case XenbusStateConnected:
1064                         scsiback_do_add_lun(info, state, phy, &vir, 1);
1065                         break;
1066                 case XenbusStateClosing:
1067                         scsiback_do_del_lun(info, state, &vir);
1068                         break;
1069                 default:
1070                         break;
1071                 }
1072                 break;
1073
1074         case VSCSIBACK_OP_UPDATEDEV_STATE:
1075                 if (device_state == XenbusStateInitialised) {
1076                         /* modify vscsi-devs/dev-x/state */
1077                         if (xenbus_printf(XBT_NIL, dev->nodename, state,
1078                                           "%d", XenbusStateConnected)) {
1079                                 pr_err("xenbus_printf error %s\n", str);
1080                                 scsiback_del_translation_entry(info, &vir);
1081                                 xenbus_printf(XBT_NIL, dev->nodename, state,
1082                                               "%d", XenbusStateClosed);
1083                         }
1084                 }
1085                 break;
1086         /* When it is necessary, processing is added here. */
1087         default:
1088                 break;
1089         }
1090 }
1091
1092 static void scsiback_do_lun_hotplug(struct vscsibk_info *info, int op)
1093 {
1094         int i;
1095         char **dir;
1096         unsigned int ndir = 0;
1097
1098         dir = xenbus_directory(XBT_NIL, info->dev->nodename, "vscsi-devs",
1099                                &ndir);
1100         if (IS_ERR(dir))
1101                 return;
1102
1103         for (i = 0; i < ndir; i++)
1104                 scsiback_do_1lun_hotplug(info, op, dir[i]);
1105
1106         kfree(dir);
1107 }
1108
1109 static void scsiback_frontend_changed(struct xenbus_device *dev,
1110                                         enum xenbus_state frontend_state)
1111 {
1112         struct vscsibk_info *info = dev_get_drvdata(&dev->dev);
1113
1114         switch (frontend_state) {
1115         case XenbusStateInitialising:
1116                 break;
1117
1118         case XenbusStateInitialised:
1119                 if (scsiback_map(info))
1120                         break;
1121
1122                 scsiback_do_lun_hotplug(info, VSCSIBACK_OP_ADD_OR_DEL_LUN);
1123                 xenbus_switch_state(dev, XenbusStateConnected);
1124                 break;
1125
1126         case XenbusStateConnected:
1127                 scsiback_do_lun_hotplug(info, VSCSIBACK_OP_UPDATEDEV_STATE);
1128
1129                 if (dev->state == XenbusStateConnected)
1130                         break;
1131
1132                 xenbus_switch_state(dev, XenbusStateConnected);
1133                 break;
1134
1135         case XenbusStateClosing:
1136                 if (info->irq)
1137                         scsiback_disconnect(info);
1138
1139                 xenbus_switch_state(dev, XenbusStateClosing);
1140                 break;
1141
1142         case XenbusStateClosed:
1143                 xenbus_switch_state(dev, XenbusStateClosed);
1144                 if (xenbus_dev_is_online(dev))
1145                         break;
1146                 /* fall through if not online */
1147         case XenbusStateUnknown:
1148                 device_unregister(&dev->dev);
1149                 break;
1150
1151         case XenbusStateReconfiguring:
1152                 scsiback_do_lun_hotplug(info, VSCSIBACK_OP_ADD_OR_DEL_LUN);
1153                 xenbus_switch_state(dev, XenbusStateReconfigured);
1154
1155                 break;
1156
1157         default:
1158                 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
1159                                         frontend_state);
1160                 break;
1161         }
1162 }
1163
1164 /*
1165   Release the translation entry specfied
1166 */
1167 static void scsiback_release_translation_entry(struct vscsibk_info *info)
1168 {
1169         struct v2p_entry *entry, *tmp;
1170         struct list_head *head = &(info->v2p_entry_lists);
1171         unsigned long flags;
1172
1173         spin_lock_irqsave(&info->v2p_lock, flags);
1174
1175         list_for_each_entry_safe(entry, tmp, head, l)
1176                 __scsiback_del_translation_entry(entry);
1177
1178         spin_unlock_irqrestore(&info->v2p_lock, flags);
1179 }
1180
1181 static int scsiback_remove(struct xenbus_device *dev)
1182 {
1183         struct vscsibk_info *info = dev_get_drvdata(&dev->dev);
1184
1185         if (info->irq)
1186                 scsiback_disconnect(info);
1187
1188         scsiback_release_translation_entry(info);
1189
1190         dev_set_drvdata(&dev->dev, NULL);
1191
1192         return 0;
1193 }
1194
1195 static int scsiback_probe(struct xenbus_device *dev,
1196                            const struct xenbus_device_id *id)
1197 {
1198         int err;
1199
1200         struct vscsibk_info *info = kzalloc(sizeof(struct vscsibk_info),
1201                                             GFP_KERNEL);
1202
1203         pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
1204
1205         if (!info) {
1206                 xenbus_dev_fatal(dev, -ENOMEM, "allocating backend structure");
1207                 return -ENOMEM;
1208         }
1209         info->dev = dev;
1210         dev_set_drvdata(&dev->dev, info);
1211
1212         info->domid = dev->otherend_id;
1213         spin_lock_init(&info->ring_lock);
1214         info->ring_error = 0;
1215         atomic_set(&info->nr_unreplied_reqs, 0);
1216         init_waitqueue_head(&info->waiting_to_free);
1217         info->dev = dev;
1218         info->irq = 0;
1219         INIT_LIST_HEAD(&info->v2p_entry_lists);
1220         spin_lock_init(&info->v2p_lock);
1221
1222         err = xenbus_printf(XBT_NIL, dev->nodename, "feature-sg-grant", "%u",
1223                             SG_ALL);
1224         if (err)
1225                 xenbus_dev_error(dev, err, "writing feature-sg-grant");
1226
1227         err = xenbus_switch_state(dev, XenbusStateInitWait);
1228         if (err)
1229                 goto fail;
1230
1231         return 0;
1232
1233 fail:
1234         pr_warn("%s failed\n", __func__);
1235         scsiback_remove(dev);
1236
1237         return err;
1238 }
1239
1240 static char *scsiback_dump_proto_id(struct scsiback_tport *tport)
1241 {
1242         switch (tport->tport_proto_id) {
1243         case SCSI_PROTOCOL_SAS:
1244                 return "SAS";
1245         case SCSI_PROTOCOL_FCP:
1246                 return "FCP";
1247         case SCSI_PROTOCOL_ISCSI:
1248                 return "iSCSI";
1249         default:
1250                 break;
1251         }
1252
1253         return "Unknown";
1254 }
1255
1256 static char *scsiback_get_fabric_wwn(struct se_portal_group *se_tpg)
1257 {
1258         struct scsiback_tpg *tpg = container_of(se_tpg,
1259                                 struct scsiback_tpg, se_tpg);
1260         struct scsiback_tport *tport = tpg->tport;
1261
1262         return &tport->tport_name[0];
1263 }
1264
1265 static u16 scsiback_get_tag(struct se_portal_group *se_tpg)
1266 {
1267         struct scsiback_tpg *tpg = container_of(se_tpg,
1268                                 struct scsiback_tpg, se_tpg);
1269         return tpg->tport_tpgt;
1270 }
1271
1272 static struct se_wwn *
1273 scsiback_make_tport(struct target_fabric_configfs *tf,
1274                      struct config_group *group,
1275                      const char *name)
1276 {
1277         struct scsiback_tport *tport;
1278         char *ptr;
1279         u64 wwpn = 0;
1280         int off = 0;
1281
1282         tport = kzalloc(sizeof(struct scsiback_tport), GFP_KERNEL);
1283         if (!tport)
1284                 return ERR_PTR(-ENOMEM);
1285
1286         tport->tport_wwpn = wwpn;
1287         /*
1288          * Determine the emulated Protocol Identifier and Target Port Name
1289          * based on the incoming configfs directory name.
1290          */
1291         ptr = strstr(name, "naa.");
1292         if (ptr) {
1293                 tport->tport_proto_id = SCSI_PROTOCOL_SAS;
1294                 goto check_len;
1295         }
1296         ptr = strstr(name, "fc.");
1297         if (ptr) {
1298                 tport->tport_proto_id = SCSI_PROTOCOL_FCP;
1299                 off = 3; /* Skip over "fc." */
1300                 goto check_len;
1301         }
1302         ptr = strstr(name, "iqn.");
1303         if (ptr) {
1304                 tport->tport_proto_id = SCSI_PROTOCOL_ISCSI;
1305                 goto check_len;
1306         }
1307
1308         pr_err("Unable to locate prefix for emulated Target Port: %s\n", name);
1309         kfree(tport);
1310         return ERR_PTR(-EINVAL);
1311
1312 check_len:
1313         if (strlen(name) >= VSCSI_NAMELEN) {
1314                 pr_err("Emulated %s Address: %s, exceeds max: %d\n", name,
1315                         scsiback_dump_proto_id(tport), VSCSI_NAMELEN);
1316                 kfree(tport);
1317                 return ERR_PTR(-EINVAL);
1318         }
1319         snprintf(&tport->tport_name[0], VSCSI_NAMELEN, "%s", &name[off]);
1320
1321         pr_debug("Allocated emulated Target %s Address: %s\n",
1322                  scsiback_dump_proto_id(tport), name);
1323
1324         return &tport->tport_wwn;
1325 }
1326
1327 static void scsiback_drop_tport(struct se_wwn *wwn)
1328 {
1329         struct scsiback_tport *tport = container_of(wwn,
1330                                 struct scsiback_tport, tport_wwn);
1331
1332         pr_debug("Deallocating emulated Target %s Address: %s\n",
1333                  scsiback_dump_proto_id(tport), tport->tport_name);
1334
1335         kfree(tport);
1336 }
1337
1338 static u32 scsiback_tpg_get_inst_index(struct se_portal_group *se_tpg)
1339 {
1340         return 1;
1341 }
1342
1343 static int scsiback_check_stop_free(struct se_cmd *se_cmd)
1344 {
1345         /*
1346          * Do not release struct se_cmd's containing a valid TMR pointer.
1347          * These will be released directly in scsiback_device_action()
1348          * with transport_generic_free_cmd().
1349          */
1350         if (se_cmd->se_cmd_flags & SCF_SCSI_TMR_CDB)
1351                 return 0;
1352
1353         transport_generic_free_cmd(se_cmd, 0);
1354         return 1;
1355 }
1356
1357 static void scsiback_release_cmd(struct se_cmd *se_cmd)
1358 {
1359         struct vscsibk_pend *pending_req = container_of(se_cmd,
1360                                 struct vscsibk_pend, se_cmd);
1361
1362         kmem_cache_free(scsiback_cachep, pending_req);
1363 }
1364
1365 static int scsiback_shutdown_session(struct se_session *se_sess)
1366 {
1367         return 0;
1368 }
1369
1370 static void scsiback_close_session(struct se_session *se_sess)
1371 {
1372 }
1373
1374 static u32 scsiback_sess_get_index(struct se_session *se_sess)
1375 {
1376         return 0;
1377 }
1378
1379 static int scsiback_write_pending(struct se_cmd *se_cmd)
1380 {
1381         /* Go ahead and process the write immediately */
1382         target_execute_cmd(se_cmd);
1383
1384         return 0;
1385 }
1386
1387 static int scsiback_write_pending_status(struct se_cmd *se_cmd)
1388 {
1389         return 0;
1390 }
1391
1392 static void scsiback_set_default_node_attrs(struct se_node_acl *nacl)
1393 {
1394 }
1395
1396 static int scsiback_get_cmd_state(struct se_cmd *se_cmd)
1397 {
1398         return 0;
1399 }
1400
1401 static int scsiback_queue_data_in(struct se_cmd *se_cmd)
1402 {
1403         struct vscsibk_pend *pending_req = container_of(se_cmd,
1404                                 struct vscsibk_pend, se_cmd);
1405
1406         pending_req->result = SAM_STAT_GOOD;
1407         scsiback_cmd_done(pending_req);
1408         return 0;
1409 }
1410
1411 static int scsiback_queue_status(struct se_cmd *se_cmd)
1412 {
1413         struct vscsibk_pend *pending_req = container_of(se_cmd,
1414                                 struct vscsibk_pend, se_cmd);
1415
1416         if (se_cmd->sense_buffer &&
1417             ((se_cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE) ||
1418              (se_cmd->se_cmd_flags & SCF_EMULATED_TASK_SENSE)))
1419                 pending_req->result = (DRIVER_SENSE << 24) |
1420                                       SAM_STAT_CHECK_CONDITION;
1421         else
1422                 pending_req->result = se_cmd->scsi_status;
1423
1424         scsiback_cmd_done(pending_req);
1425         return 0;
1426 }
1427
1428 static void scsiback_queue_tm_rsp(struct se_cmd *se_cmd)
1429 {
1430         struct se_tmr_req *se_tmr = se_cmd->se_tmr_req;
1431         struct scsiback_tmr *tmr = se_tmr->fabric_tmr_ptr;
1432
1433         atomic_set(&tmr->tmr_complete, 1);
1434         wake_up(&tmr->tmr_wait);
1435 }
1436
1437 static void scsiback_aborted_task(struct se_cmd *se_cmd)
1438 {
1439 }
1440
1441 static ssize_t scsiback_tpg_param_show_alias(struct se_portal_group *se_tpg,
1442                                              char *page)
1443 {
1444         struct scsiback_tpg *tpg = container_of(se_tpg, struct scsiback_tpg,
1445                                                 se_tpg);
1446         ssize_t rb;
1447
1448         mutex_lock(&tpg->tv_tpg_mutex);
1449         rb = snprintf(page, PAGE_SIZE, "%s\n", tpg->param_alias);
1450         mutex_unlock(&tpg->tv_tpg_mutex);
1451
1452         return rb;
1453 }
1454
1455 static ssize_t scsiback_tpg_param_store_alias(struct se_portal_group *se_tpg,
1456                                               const char *page, size_t count)
1457 {
1458         struct scsiback_tpg *tpg = container_of(se_tpg, struct scsiback_tpg,
1459                                                 se_tpg);
1460         int len;
1461
1462         if (strlen(page) >= VSCSI_NAMELEN) {
1463                 pr_err("param alias: %s, exceeds max: %d\n", page,
1464                         VSCSI_NAMELEN);
1465                 return -EINVAL;
1466         }
1467
1468         mutex_lock(&tpg->tv_tpg_mutex);
1469         len = snprintf(tpg->param_alias, VSCSI_NAMELEN, "%s", page);
1470         if (tpg->param_alias[len - 1] == '\n')
1471                 tpg->param_alias[len - 1] = '\0';
1472         mutex_unlock(&tpg->tv_tpg_mutex);
1473
1474         return count;
1475 }
1476
1477 TF_TPG_PARAM_ATTR(scsiback, alias, S_IRUGO | S_IWUSR);
1478
1479 static struct configfs_attribute *scsiback_param_attrs[] = {
1480         &scsiback_tpg_param_alias.attr,
1481         NULL,
1482 };
1483
1484 static int scsiback_make_nexus(struct scsiback_tpg *tpg,
1485                                 const char *name)
1486 {
1487         struct se_portal_group *se_tpg;
1488         struct se_session *se_sess;
1489         struct scsiback_nexus *tv_nexus;
1490
1491         mutex_lock(&tpg->tv_tpg_mutex);
1492         if (tpg->tpg_nexus) {
1493                 mutex_unlock(&tpg->tv_tpg_mutex);
1494                 pr_debug("tpg->tpg_nexus already exists\n");
1495                 return -EEXIST;
1496         }
1497         se_tpg = &tpg->se_tpg;
1498
1499         tv_nexus = kzalloc(sizeof(struct scsiback_nexus), GFP_KERNEL);
1500         if (!tv_nexus) {
1501                 mutex_unlock(&tpg->tv_tpg_mutex);
1502                 return -ENOMEM;
1503         }
1504         /*
1505          * Initialize the struct se_session pointer
1506          */
1507         tv_nexus->tvn_se_sess = transport_init_session(TARGET_PROT_NORMAL);
1508         if (IS_ERR(tv_nexus->tvn_se_sess)) {
1509                 mutex_unlock(&tpg->tv_tpg_mutex);
1510                 kfree(tv_nexus);
1511                 return -ENOMEM;
1512         }
1513         se_sess = tv_nexus->tvn_se_sess;
1514         /*
1515          * Since we are running in 'demo mode' this call with generate a
1516          * struct se_node_acl for the scsiback struct se_portal_group with
1517          * the SCSI Initiator port name of the passed configfs group 'name'.
1518          */
1519         tv_nexus->tvn_se_sess->se_node_acl = core_tpg_check_initiator_node_acl(
1520                                 se_tpg, (unsigned char *)name);
1521         if (!tv_nexus->tvn_se_sess->se_node_acl) {
1522                 mutex_unlock(&tpg->tv_tpg_mutex);
1523                 pr_debug("core_tpg_check_initiator_node_acl() failed for %s\n",
1524                          name);
1525                 goto out;
1526         }
1527         /* Now register the TCM pvscsi virtual I_T Nexus as active. */
1528         transport_register_session(se_tpg, tv_nexus->tvn_se_sess->se_node_acl,
1529                         tv_nexus->tvn_se_sess, tv_nexus);
1530         tpg->tpg_nexus = tv_nexus;
1531
1532         mutex_unlock(&tpg->tv_tpg_mutex);
1533         return 0;
1534
1535 out:
1536         transport_free_session(se_sess);
1537         kfree(tv_nexus);
1538         return -ENOMEM;
1539 }
1540
1541 static int scsiback_drop_nexus(struct scsiback_tpg *tpg)
1542 {
1543         struct se_session *se_sess;
1544         struct scsiback_nexus *tv_nexus;
1545
1546         mutex_lock(&tpg->tv_tpg_mutex);
1547         tv_nexus = tpg->tpg_nexus;
1548         if (!tv_nexus) {
1549                 mutex_unlock(&tpg->tv_tpg_mutex);
1550                 return -ENODEV;
1551         }
1552
1553         se_sess = tv_nexus->tvn_se_sess;
1554         if (!se_sess) {
1555                 mutex_unlock(&tpg->tv_tpg_mutex);
1556                 return -ENODEV;
1557         }
1558
1559         if (tpg->tv_tpg_port_count != 0) {
1560                 mutex_unlock(&tpg->tv_tpg_mutex);
1561                 pr_err("Unable to remove xen-pvscsi I_T Nexus with active TPG port count: %d\n",
1562                         tpg->tv_tpg_port_count);
1563                 return -EBUSY;
1564         }
1565
1566         if (tpg->tv_tpg_fe_count != 0) {
1567                 mutex_unlock(&tpg->tv_tpg_mutex);
1568                 pr_err("Unable to remove xen-pvscsi I_T Nexus with active TPG frontend count: %d\n",
1569                         tpg->tv_tpg_fe_count);
1570                 return -EBUSY;
1571         }
1572
1573         pr_debug("Removing I_T Nexus to emulated %s Initiator Port: %s\n",
1574                 scsiback_dump_proto_id(tpg->tport),
1575                 tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
1576
1577         /*
1578          * Release the SCSI I_T Nexus to the emulated xen-pvscsi Target Port
1579          */
1580         transport_deregister_session(tv_nexus->tvn_se_sess);
1581         tpg->tpg_nexus = NULL;
1582         mutex_unlock(&tpg->tv_tpg_mutex);
1583
1584         kfree(tv_nexus);
1585         return 0;
1586 }
1587
1588 static ssize_t scsiback_tpg_show_nexus(struct se_portal_group *se_tpg,
1589                                         char *page)
1590 {
1591         struct scsiback_tpg *tpg = container_of(se_tpg,
1592                                 struct scsiback_tpg, se_tpg);
1593         struct scsiback_nexus *tv_nexus;
1594         ssize_t ret;
1595
1596         mutex_lock(&tpg->tv_tpg_mutex);
1597         tv_nexus = tpg->tpg_nexus;
1598         if (!tv_nexus) {
1599                 mutex_unlock(&tpg->tv_tpg_mutex);
1600                 return -ENODEV;
1601         }
1602         ret = snprintf(page, PAGE_SIZE, "%s\n",
1603                         tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
1604         mutex_unlock(&tpg->tv_tpg_mutex);
1605
1606         return ret;
1607 }
1608
1609 static ssize_t scsiback_tpg_store_nexus(struct se_portal_group *se_tpg,
1610                                          const char *page,
1611                                          size_t count)
1612 {
1613         struct scsiback_tpg *tpg = container_of(se_tpg,
1614                                 struct scsiback_tpg, se_tpg);
1615         struct scsiback_tport *tport_wwn = tpg->tport;
1616         unsigned char i_port[VSCSI_NAMELEN], *ptr, *port_ptr;
1617         int ret;
1618         /*
1619          * Shutdown the active I_T nexus if 'NULL' is passed.
1620          */
1621         if (!strncmp(page, "NULL", 4)) {
1622                 ret = scsiback_drop_nexus(tpg);
1623                 return (!ret) ? count : ret;
1624         }
1625         /*
1626          * Otherwise make sure the passed virtual Initiator port WWN matches
1627          * the fabric protocol_id set in scsiback_make_tport(), and call
1628          * scsiback_make_nexus().
1629          */
1630         if (strlen(page) >= VSCSI_NAMELEN) {
1631                 pr_err("Emulated NAA Sas Address: %s, exceeds max: %d\n",
1632                         page, VSCSI_NAMELEN);
1633                 return -EINVAL;
1634         }
1635         snprintf(&i_port[0], VSCSI_NAMELEN, "%s", page);
1636
1637         ptr = strstr(i_port, "naa.");
1638         if (ptr) {
1639                 if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_SAS) {
1640                         pr_err("Passed SAS Initiator Port %s does not match target port protoid: %s\n",
1641                                 i_port, scsiback_dump_proto_id(tport_wwn));
1642                         return -EINVAL;
1643                 }
1644                 port_ptr = &i_port[0];
1645                 goto check_newline;
1646         }
1647         ptr = strstr(i_port, "fc.");
1648         if (ptr) {
1649                 if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_FCP) {
1650                         pr_err("Passed FCP Initiator Port %s does not match target port protoid: %s\n",
1651                                 i_port, scsiback_dump_proto_id(tport_wwn));
1652                         return -EINVAL;
1653                 }
1654                 port_ptr = &i_port[3]; /* Skip over "fc." */
1655                 goto check_newline;
1656         }
1657         ptr = strstr(i_port, "iqn.");
1658         if (ptr) {
1659                 if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_ISCSI) {
1660                         pr_err("Passed iSCSI Initiator Port %s does not match target port protoid: %s\n",
1661                                 i_port, scsiback_dump_proto_id(tport_wwn));
1662                         return -EINVAL;
1663                 }
1664                 port_ptr = &i_port[0];
1665                 goto check_newline;
1666         }
1667         pr_err("Unable to locate prefix for emulated Initiator Port: %s\n",
1668                 i_port);
1669         return -EINVAL;
1670         /*
1671          * Clear any trailing newline for the NAA WWN
1672          */
1673 check_newline:
1674         if (i_port[strlen(i_port) - 1] == '\n')
1675                 i_port[strlen(i_port) - 1] = '\0';
1676
1677         ret = scsiback_make_nexus(tpg, port_ptr);
1678         if (ret < 0)
1679                 return ret;
1680
1681         return count;
1682 }
1683
1684 TF_TPG_BASE_ATTR(scsiback, nexus, S_IRUGO | S_IWUSR);
1685
1686 static struct configfs_attribute *scsiback_tpg_attrs[] = {
1687         &scsiback_tpg_nexus.attr,
1688         NULL,
1689 };
1690
1691 static ssize_t
1692 scsiback_wwn_show_attr_version(struct target_fabric_configfs *tf,
1693                                 char *page)
1694 {
1695         return sprintf(page, "xen-pvscsi fabric module %s on %s/%s on "
1696                 UTS_RELEASE"\n",
1697                 VSCSI_VERSION, utsname()->sysname, utsname()->machine);
1698 }
1699
1700 TF_WWN_ATTR_RO(scsiback, version);
1701
1702 static struct configfs_attribute *scsiback_wwn_attrs[] = {
1703         &scsiback_wwn_version.attr,
1704         NULL,
1705 };
1706
1707 static char *scsiback_get_fabric_name(void)
1708 {
1709         return "xen-pvscsi";
1710 }
1711
1712 static int scsiback_port_link(struct se_portal_group *se_tpg,
1713                                struct se_lun *lun)
1714 {
1715         struct scsiback_tpg *tpg = container_of(se_tpg,
1716                                 struct scsiback_tpg, se_tpg);
1717
1718         mutex_lock(&tpg->tv_tpg_mutex);
1719         tpg->tv_tpg_port_count++;
1720         mutex_unlock(&tpg->tv_tpg_mutex);
1721
1722         return 0;
1723 }
1724
1725 static void scsiback_port_unlink(struct se_portal_group *se_tpg,
1726                                   struct se_lun *lun)
1727 {
1728         struct scsiback_tpg *tpg = container_of(se_tpg,
1729                                 struct scsiback_tpg, se_tpg);
1730
1731         mutex_lock(&tpg->tv_tpg_mutex);
1732         tpg->tv_tpg_port_count--;
1733         mutex_unlock(&tpg->tv_tpg_mutex);
1734 }
1735
1736 static struct se_portal_group *
1737 scsiback_make_tpg(struct se_wwn *wwn,
1738                    struct config_group *group,
1739                    const char *name)
1740 {
1741         struct scsiback_tport *tport = container_of(wwn,
1742                         struct scsiback_tport, tport_wwn);
1743
1744         struct scsiback_tpg *tpg;
1745         u16 tpgt;
1746         int ret;
1747
1748         if (strstr(name, "tpgt_") != name)
1749                 return ERR_PTR(-EINVAL);
1750         ret = kstrtou16(name + 5, 10, &tpgt);
1751         if (ret)
1752                 return ERR_PTR(ret);
1753
1754         tpg = kzalloc(sizeof(struct scsiback_tpg), GFP_KERNEL);
1755         if (!tpg)
1756                 return ERR_PTR(-ENOMEM);
1757
1758         mutex_init(&tpg->tv_tpg_mutex);
1759         INIT_LIST_HEAD(&tpg->tv_tpg_list);
1760         INIT_LIST_HEAD(&tpg->info_list);
1761         tpg->tport = tport;
1762         tpg->tport_tpgt = tpgt;
1763
1764         ret = core_tpg_register(wwn, &tpg->se_tpg, tport->tport_proto_id);
1765         if (ret < 0) {
1766                 kfree(tpg);
1767                 return NULL;
1768         }
1769         mutex_lock(&scsiback_mutex);
1770         list_add_tail(&tpg->tv_tpg_list, &scsiback_list);
1771         mutex_unlock(&scsiback_mutex);
1772
1773         return &tpg->se_tpg;
1774 }
1775
1776 static void scsiback_drop_tpg(struct se_portal_group *se_tpg)
1777 {
1778         struct scsiback_tpg *tpg = container_of(se_tpg,
1779                                 struct scsiback_tpg, se_tpg);
1780
1781         mutex_lock(&scsiback_mutex);
1782         list_del(&tpg->tv_tpg_list);
1783         mutex_unlock(&scsiback_mutex);
1784         /*
1785          * Release the virtual I_T Nexus for this xen-pvscsi TPG
1786          */
1787         scsiback_drop_nexus(tpg);
1788         /*
1789          * Deregister the se_tpg from TCM.
1790          */
1791         core_tpg_deregister(se_tpg);
1792         kfree(tpg);
1793 }
1794
1795 static int scsiback_check_true(struct se_portal_group *se_tpg)
1796 {
1797         return 1;
1798 }
1799
1800 static int scsiback_check_false(struct se_portal_group *se_tpg)
1801 {
1802         return 0;
1803 }
1804
1805 static const struct target_core_fabric_ops scsiback_ops = {
1806         .module                         = THIS_MODULE,
1807         .name                           = "xen-pvscsi",
1808         .get_fabric_name                = scsiback_get_fabric_name,
1809         .tpg_get_wwn                    = scsiback_get_fabric_wwn,
1810         .tpg_get_tag                    = scsiback_get_tag,
1811         .tpg_check_demo_mode            = scsiback_check_true,
1812         .tpg_check_demo_mode_cache      = scsiback_check_true,
1813         .tpg_check_demo_mode_write_protect = scsiback_check_false,
1814         .tpg_check_prod_mode_write_protect = scsiback_check_false,
1815         .tpg_get_inst_index             = scsiback_tpg_get_inst_index,
1816         .check_stop_free                = scsiback_check_stop_free,
1817         .release_cmd                    = scsiback_release_cmd,
1818         .shutdown_session               = scsiback_shutdown_session,
1819         .close_session                  = scsiback_close_session,
1820         .sess_get_index                 = scsiback_sess_get_index,
1821         .sess_get_initiator_sid         = NULL,
1822         .write_pending                  = scsiback_write_pending,
1823         .write_pending_status           = scsiback_write_pending_status,
1824         .set_default_node_attributes    = scsiback_set_default_node_attrs,
1825         .get_cmd_state                  = scsiback_get_cmd_state,
1826         .queue_data_in                  = scsiback_queue_data_in,
1827         .queue_status                   = scsiback_queue_status,
1828         .queue_tm_rsp                   = scsiback_queue_tm_rsp,
1829         .aborted_task                   = scsiback_aborted_task,
1830         /*
1831          * Setup callers for generic logic in target_core_fabric_configfs.c
1832          */
1833         .fabric_make_wwn                = scsiback_make_tport,
1834         .fabric_drop_wwn                = scsiback_drop_tport,
1835         .fabric_make_tpg                = scsiback_make_tpg,
1836         .fabric_drop_tpg                = scsiback_drop_tpg,
1837         .fabric_post_link               = scsiback_port_link,
1838         .fabric_pre_unlink              = scsiback_port_unlink,
1839
1840         .tfc_wwn_attrs                  = scsiback_wwn_attrs,
1841         .tfc_tpg_base_attrs             = scsiback_tpg_attrs,
1842         .tfc_tpg_param_attrs            = scsiback_param_attrs,
1843 };
1844
1845 static const struct xenbus_device_id scsiback_ids[] = {
1846         { "vscsi" },
1847         { "" }
1848 };
1849
1850 static struct xenbus_driver scsiback_driver = {
1851         .ids                    = scsiback_ids,
1852         .probe                  = scsiback_probe,
1853         .remove                 = scsiback_remove,
1854         .otherend_changed       = scsiback_frontend_changed
1855 };
1856
1857 static void scsiback_init_pend(void *p)
1858 {
1859         struct vscsibk_pend *pend = p;
1860         int i;
1861
1862         memset(pend, 0, sizeof(*pend));
1863         for (i = 0; i < VSCSI_MAX_GRANTS; i++)
1864                 pend->grant_handles[i] = SCSIBACK_INVALID_HANDLE;
1865 }
1866
1867 static int __init scsiback_init(void)
1868 {
1869         int ret;
1870
1871         if (!xen_domain())
1872                 return -ENODEV;
1873
1874         pr_debug("xen-pvscsi: fabric module %s on %s/%s on "UTS_RELEASE"\n",
1875                  VSCSI_VERSION, utsname()->sysname, utsname()->machine);
1876
1877         scsiback_cachep = kmem_cache_create("vscsiif_cache",
1878                 sizeof(struct vscsibk_pend), 0, 0, scsiback_init_pend);
1879         if (!scsiback_cachep)
1880                 return -ENOMEM;
1881
1882         ret = xenbus_register_backend(&scsiback_driver);
1883         if (ret)
1884                 goto out_cache_destroy;
1885
1886         ret = target_register_template(&scsiback_ops);
1887         if (ret)
1888                 goto out_unregister_xenbus;
1889
1890         return 0;
1891
1892 out_unregister_xenbus:
1893         xenbus_unregister_driver(&scsiback_driver);
1894 out_cache_destroy:
1895         kmem_cache_destroy(scsiback_cachep);
1896         pr_err("%s: error %d\n", __func__, ret);
1897         return ret;
1898 }
1899
1900 static void __exit scsiback_exit(void)
1901 {
1902         struct page *page;
1903
1904         while (free_pages_num) {
1905                 if (get_free_page(&page))
1906                         BUG();
1907                 gnttab_free_pages(1, &page);
1908         }
1909         target_unregister_template(&scsiback_ops);
1910         xenbus_unregister_driver(&scsiback_driver);
1911         kmem_cache_destroy(scsiback_cachep);
1912 }
1913
1914 module_init(scsiback_init);
1915 module_exit(scsiback_exit);
1916
1917 MODULE_DESCRIPTION("Xen SCSI backend driver");
1918 MODULE_LICENSE("Dual BSD/GPL");
1919 MODULE_ALIAS("xen-backend:vscsi");
1920 MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");